1. Field of the Invention
The present invention generally relates to a memory, a driving method thereof, and a manufacturing method thereof, and more particularly, to a magnetic memory, a driving method thereof, and a manufacturing method thereof.
2. Description of Related Art
FIG. 1 is a partial view of a conventional magnetic memory disclosed in U.S. Pat. No. 6,834,005. Referring to FIG. 1, the magnetic memory 100 includes a substrate 110, a magnetic metal track 120, a read device 130, and a write device 140. The magnetic metal track 120 includes a plurality of magnetic memory cells 122 connected with each other, and each of the magnetic memory cells 122 includes a memory portion 122M and a notch portion 122W. Generally speaking, the notch portions 122W are periodically arranged in the magnetic memory 100 to define the positions and sizes of the memory portions 122M.
Based on the structure described above and the physical characteristic of the magnetic metal track 120 itself, the magnetic metal track 120 can be used for recording bit data, wherein the memory portions 122M are used for recording the bit data of “0” or “1”, and the notch portions 122W are used for separating the bit data recorded in adjacent memory portions 122M. As shown in FIG. 1, the bit data of “0” or “1” is defined in each of the memory portions 122M according to a magnetic moment direction D in the area of the memory portion 122M, wherein the area of the memory portion 122M is usually referred to as a magnetic domain. On the other hand, because the magnetic moment direction (not shown) in the area of each of the notch portions 122W is different from the magnetic moment directions D in the areas of the adjacent two memory portions 122M, the bit data recorded in the adjacent two magnetic domains can be separated by the notch portion 122W, wherein the area of the notch portion 122W is usually referred to as a domain wall. As shown in FIG. 1, the memory portion 122M (the magnetic domain) and the notch portion 122W (the domain wall) in each of the magnetic memory cells 122 are adjacent to each other.
However, the notch portions 122W are very difficult to be fabricated and the process window thereof is very low. Accordingly, the fabrication yield of the periodically arranged notch portions 122W cannot be improved.
Conventionally, the bit data recorded in the magnetic memory cells 122 is read by using the read device 130, and new bit data is written into the magnetic memory cells 122 by using the write device 140. However, herein the term “write” does not mean that the magnetic memory cell 122 will record two bit data after the new bit data is written into the magnetic memory cell 122; instead, it means that the original bit data in the magnetic memory cell 122 is “updated”.
The write device 140 changes the magnetic moment direction D of the memory portion 122M located above the write device 140 by using a magnetic leakage field 141. Thus, the bit data in the memory portion 122M has to be located above the write device 140 in order to allow the write device 140 to write data, wherein the bit data is shifted out of or into the memory portion 122M by a high current pulse HP received by the magnetic metal track 120. To be specific, during an shift period, a high current pulse HP is supplied to the magnetic metal track 120. In this case, the bit data is shifted out of the current memory portion 122M and into the adjacent memory portion 122M by the high current pulse HP. In other words, during the shift period, the bit data in each of the memory portions 122M is pushed into a next or a previous memory portion 122M by the high current pulse HP, wherein the shifting direction of the bit data is determined by the high current pulse HP. A read/write period is entered after the shift period, and herein each bit data remains in the memory portion 122M so that the write device 140 can write new bit data into the memory portion 122M located above the write device 140. Similarly, the read device 130 can read the bit data from the memory portion 122M located above the read device 130 during the read/write period; however, the operation details will not be described herein.
Generally, a high current pulse HP between 107 amp/cm2 and 108 amp/cm2 or even higher is required to shift a bit data out of or into a memory portion 122M. However, such an electrical parameter increases the power consumption of the magnetic memory 100.